Lead Screw Nut Selection

BFW General Purpose-Backlash

The Kerk® BFW Series general purpose “free-wheeling” nut is for applications not requiring anti-backlash and wear compensation. It provides effective power transmission at minimum cost, and features long life, self-lubricating polyacetal acme lead screw nuts. Kerkite® Composite Polymers are also available as standard options. The secure mounting and convenience of a circular flange is standard on the BFW nuts with triangular flange and thread mounting as an option. Many custom configurations are available. Acme lead screws are 303 stainless steel with extended life, custom Kerkote® TFE coating optional. Assemblies can be supplied cut-to-length or with ends machined to customer requirements.

Dimensional Drawings
+

Please note: Metric numbers are for reference only.

BFWB SERIES: BARREL MOUNT

Screw
Ø

Nut
Ø

Nut
Length

Nut
Flats

Dynamic
Load

Drag
Torque

A
in.
(mm)

B
in.
(mm)

C
in.
(mm)

D
in.
(mm)

lbs.
(Kg)

oz.-in.
(Nm)

5/64
(2)

.22
(5.5)

.32
(8)

.2
(4.5)

10
(4.5)

Free
Wheeling

BFWR SERIES: FLANGE MOUNT(Rectangle)

ScrewØ

NutØ

Nut
Length

Flange
Height

Flange
Width

Flange
Thickness

Slot
Width

Bolt
Circle Ø

Dynamic
Load

Drag
Torque

A
inch
(mm)

B
inch
(mm)

C
inch
(mm)

D1
inch
(mm)

D
inch
(mm)

E
inch
(mm)

F
inch
(mm)

G
inch
(mm)

lbs.
(Kg)

oz.-in.
(Nm)

5/64
(2)

0.22
(5.5)

0.32
(8)

0.22
(5.5)

0.47
(11.9)

0.08
(2.0)

0.07
(1.8)

0.35
(9)

10
(4.5)

Free
Wheeling

1/8
(3)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

0.132
(3.3)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

9/64
(3.6)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

5/32
(4)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

3/16
(5)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

7/32
(5.6)

.40
(10.2)

.50
(13)

.40
(10.2)

.75
(19.1)

.13
(3.2)

.120
(3.05)

.600
(15.24)

25
(11)

Free
Wheeling

BFWT SERIES: THREAD MOUNT

Screw
Ø

Nut
Ø

Nut
Length

Thread

Thread
Length

Dynamic
Load

A
in.
(mm)

B
in.
(mm)

C
in.
(mm)

M
in.

N
in.
(mm)

lbs.
(Kg)

1/8
(3)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

0.132
(3.3)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

9/64
(3.6)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

5/32
(4)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

3/16
(5)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

7/32
(5.6)

.40
(10.2)

.50
(13)

3/8-24

0.187
(4.75)

25
(11)

1/4
(6)

.63
(15.9)

1.0
(25.4)

9/16-18

0.187
(4.75)

50
(20)

5/16
(8)

.75
(19.1)

1.0
(25.4)

5/8-18

0.250
(6.35)

75
(35)

3/8
(10)

.75
(19.1)

1.0
(25.4)

5/8-18

0.250
(6.35)

75
(35)

7/16
(11)

1.00
(25.4)

1.5
(38)

15/16-16

0.375
(9.53)

90
(40)

1/2
(13)

1.00
(25.4)

1.5
(38)

15/16-16

0.375
(9.53)

150
(68)

5/8
(16)

1.00
(25.4)

1.5
(38)

15/16-16

0.375
(9.53)

225
(100)

3/4
(19)

1.50
(38.1)

2.0
(51)

1 3/8-16

0.500
(12.70)

350
(160)

7/8
(22)

1.50
(38.1)

2.0
(51)

1 3/8-16

0.500
(12.70)

500
(227)

15/16
(24)

1.50
(38.1)

2.0
(51)

1 3/8-16

0.500
(12.70)

500
(227)

BFWA SERIES: FLANGE MOUNT (Triangular)

Screw
∅

Nut
∅

Nut
Length

Flange
∅

Flange
Length

Mounting
Hole ∅

Bolt
Circle ∅

Dynamic
Load

A
inch
(mm)

B
inch
(mm)

C
inch
(mm)

D
inch
(mm)

E
inch
(mm)

F
inch
(mm)

G
inch
(mm)

lbs.
(kg)

1/4
(6)

0.50
(12.7)

1.0
(25.4)

1.00
(25.4)

0.17
(4.3)

0.143
(3.63)

0.750
(19.05)

50
(20)

5/16
(8)

0.50
(12.7)

1.9
(48.3)

1.50
(38.1)

0.17
(4.3)

0.143
(3.63)

0.75
(19.1)

75
(35)

3/8
(10)

0.66
(16.6)

1.9
(48.3)

1.50
(38.1)

0.17
(4.3)

0.197
(5.00)

1.125
(28.58)

75
(35)

7/16
(11)

0.75
(19.1)

1.9
(48.3)

1.50
(38.1)

0.17
(4.3)

0.197
(5.00)

1.125
(28.58)

90
(40)

1/2
(13)

0.75
(19.1)

1.9
(48.3)

1.50
(38.1)

0.17
(4.3)

0.197
(5.00)

1.125
(28.58)

150
(68)

BFWF SERIES: FLANGE MOUNT (Round)

Screw
∅

Nut
∅

Nut
Length

Flange
∅

Flange
Length

Mounting
Hole ∅

Bolt
Circle ∅

Dynamic
Load

A
inch
(mm)

B
inch
(mm)

C
inch
(mm)

D
inch
(mm)

E
inch
(mm)

F
inch
(mm)

G
inch
(mm)

lbs.
(kg)

1/4
(6)

0.50
(12.7)

1.0
(25.4)

1.00
(25.4)

0.19
(4.8)

0.140
(3.56)

0.750
(19.05)

50
(20)

5/16
(8)

0.63
(15.9)

1.0
(25.4)

1.13
(28.7)

0.19
(4.8)

0.140
(3.56)

0.875
(22.23)

75
(35)

3/8
(10)

0.63
(15.9)

1.0
(25.4)

1.13
(28.7)

0.19
(4.8)

0.140
(3.56)

0.875
(22.23)

75
(35)

7/16
(11)

0.75
(19.1)

1.5
(38)

1.50
(38.1)

0.19
(4.8)

0.203
(5.16)

1.125
(28.58)

90
(40)

1/2
(13)

0.75
(19.1)

1.5
(38)

1.50
(38.1)

0.19
(4.8)

0.203
(5.16)

1.125
(28.58)

150
(68)

5/8
(16)

0.88
(22.2)

1.5
(38)

1.50
(38.1)

0.19
(4.8)

0.203
(5.16)

1.188
(30.18)

225
(100)

3/4
(19)

1.12
(28.4)

2.0
(51)

1.75
(44.4)

0.25
(6.4)

0.203
(5.16)

1.438
(36.53)

350
(160)

7/8
(22)

1.50
(38.1)

2.0
(51)

2.25
(57.1)

0.25
(6.4)

0.203
(5.16)

1.875
(47.63)

500
(227)

15/16
(24)

1.50
(38.1)

2.0
(51)

2.25
(57.1)

0.25
(6.4)

0.203
(5.16)

1.875
(47.63)

500
(227)

Diameter and Lead Options
+

5/64" (2 mm) Diameter Lead Screw. Diameter Code 008

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %

in

mm

In

mm

in

mm

0.012

0.3

0012

0.079

2.01

0.068

1.73

24**

0.016

0.4

0016

0.075

1.91

0.058

1.47

30**

0.02

0.5

0020

0.077

1.96

0.057

1.45

36**

0.039

1

0039

0.079

2.01

0.059

1.5

52**

0.079

2

0079

0.077

1.96

0.057

1.45

66**

** Listed efficiency for Micro screws are theoretical values based on non-coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.1/8" (3.2 mm) Diameter Lead Screw. Diameter Code 012

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.024

0.61

0024

0.129

3.28

0.093

2.36

44

0.039

1

0039

0.129

3.28

0.094

2.39

57

0.048

1.22

0048

0.129

3.28

0.093

2.36

61

0.075

1.91

0075

0.129

3.28

0.093

2.36

70

0.096

2.44

0096

√

0.129

3.28

0.093

2.36

75

0.125

3.18

0125

LH Only

0.125

3.18

0.078

1.98

80

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.0.132" (3.3 mm)) Diameter Lead Screw. Diameter Code 013

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

In

mm

in

mm

0.02

0.5

0020

0.132

3.35

0.104

2.64

42

0.039

1

0039

0.132

3.35

0.08

2.03

61

0.079

2.00.

0079

0.132

3.35

0.08

2.03

75

0.157

4

0157

0.132

3.35

0.08

2.03

84

0.315

8

0315

0.132

3.35

0.08

2.03

87

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.9/64" (3.6 mm) Diameter Lead Screw. Diameter Code 014

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.012

0.3

0012

0.14

3.56

0.123

3.12

26

0.024

0.61

0024

0.14

3.56

0.105

2.67

43

0.048

1.22

0048

0.14

3.56

0.081

2.06

62

0.096

2.44

0096

0.14

3.56

0.081

2.06

75

0.394

10

0394

0.14

3.56

0.102

2.59

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.5/32" (4 mm) Diameter Lead Screw. Diameter Code 016

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.033

0.84

0033

√

0.156

3.96

0.116

2.95

45

0.05

1.27

0050

LH Only

0.156

3.96

0.096

2.44

59

0.094

2.39

0094

0.164

4.17

0.128

3.25

67

0.125

3.18

0125

0.168

4.27

0.13

3.3

74

0.25

6.35

0250

0.156

3.96

0.13

3.3

83

0.375

9.53

0375

0.156

3.96

0.13

3.3

85

0.5

12.7

0500

0.156

3.96

0.13

3.3

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.3/16" (5 mm) Diameter Lead Screw. Diameter Code 018

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.02

0.5

0020

0.188

4.78

0.163

4.14

30

0.025

0.64

0025

0.188

4.78

0.15

3.81

39

0.039

1

0039

0.188

4.78

0.144

3.66

47

0.05

1.27

0050

0.188

4.78

0.124

3.15

58

0.1

2.54

0100

0.188

4.78

0.136

3.45

69

0.1875

4.76

0188

0.188

4.78

0.167

4.24

78

0.2

5.08

0200

0.188

4.78

0.124

3.15

82

0.375

9.53

0375

0.188

4.78

0.161

4.09

84

0.4

10.16

0400

0.188

4.78

0.124

3.15

84

0.427

10.85

0427

0.188

4.78

0.162

4.11

85

0.5

12.7

0500

√

0.188

4.78

0.142

3.61

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.7/32" (5.6 mm) Diameter Lead Screw. Diameter Code 021

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.024

0.61

0024

0.218

5.54

0.181

4.6

31

0.03125

0.79

0031

0.204

5.18

0.16

4.06

39

0.048

1.22

0048

0.216

5.49

0.156

3.96

50

0.05

1.27

0050

0.2

5.08

0.135

3.43

52

0.0625

1.59

0063

0.218

5.54

0.142

3.61

60

0.096

2.44

0096

0.218

5.54

0.156

3.96

66

0.192

4.88

0192

0.218

5.54

0.156

3.96

78

0.25

6.35

0250

√

0.204

5.18

0.14

3.56

81

0.384

9.75

0384

0.218

5.54

0.159

4.04

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.1/4" (6 mm) Diameter Lead Screw. Diameter Code 025

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.024

0.61

0024

0.25

6.35

0.218

5.54

28

0.025

0.64

0025

0.25

6.35

0.214

5.44

30

0.03125

0.79

0031

0.25

6.35

0.208

5.28

34

0.039

1

0039

0.25

6.35

0.19

4.83

40

0.048

1.22

0048

0.25

6.35

0.19

4.83

45

0.05

1.27

0050

√

0.25

6.35

0.191

4.85

46

0.059

1.5

0059

0.25

6.35

0.172

4.37

52

0.0625

1.59

0063

0.25

6.35

0.17

4.32

52

0.079

2

0079

0.25

6.35

0.17

4.32

59

0.096

2.44

0096

0.25

6.35

0.19

4.83

61

0.1

2.54

0100

0.25

6.35

0.19

4.83

62

0.118

3

0118

0.25

6.35

0.175

4.45

68

0.125

3.18

0125

0.25

6.35

0.19

4.83

67

0.197

5

0197

0.25

6.35

0.172

4.37

72

0.2

5.08

0200

0.25

6.35

0.17

4.32

65

0.25

6.35

0250

√

0.25

6.35

0.168

4.27

79

0.3125

7.94

0313

0.25

6.35

0.184

4.67

81

0.333

8.46

0333

0.25

6.35

0.17

4.32

82

0.394

10

0394

0.25

6.35

0.17

4.32

78

0.4

10.16

0400

0.25

6.35

0.17

4.32

84

0.5

12.7

0500

√

0.25

6.35

0.169

4.29

85

0.75

19.05

0750

0.25

6.35

0.17

4.32

86

1

25.4

1000

√

0.25

6.35

0.17

4.32

84

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.5/16" (8 mm) Diameter Lead Screw. Diameter Code 031

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.057

1.44

0057

0.315

8

0.243

6.71

43

0.0741

1.88

0074

0.312

7.92

0.211

5.36

51

0.111

2.82

0111

0.312

7.92

232

5.89

60

0.167

4.24

0167

0.312

7.92

0.211

5.36

69

0.25

6.35

0250

0.312

7.92

0.234

5.94

76

0.5

12.7

0500

√

0.312

7.92

0.232

5.89

83

0.8

20.32

0800

0.306

7.77

0.243

6.17

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 3/8" (10 mm) Diameter Lead Screw. Diameter Code 037

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.025

0.64

0025

0.375

9.53

0.337

8.56

21

0.039

1

0039

0.394

10.01

0.35

8.89

28

0.04167

1.06

0042

0.375

9.53

0.32

8.13

34

0.05

1.27

0050

√

0.375

9.53

0.301

7.65

36

0.055

1.4

0055

0.375

9.53

0.303

7.7

38

0.059

1.5

0059

√

0.389

9.88

0.313

7.95

38

0.0625

1.59

0063

√

0.375

9.53

0.295

7.49

41

0.068

1.73

0068

0.388

9.86

0.295

7.49

42

0.079

2

0079

0.375

9.53

0.264

6.71

47

0.0833

2.12

0083

0.375

9.53

0.293

7.44

48

0.1

2.54

0100

√

0.375

9.53

0.266

6.76

53

0.125

3.18

0125

0.375

9.53

0.295

7.49

59

0.157

4

0157

0.375

9.53

0.274

6.96

65

0.1667

4.23

0167

0.371

9.42

0.261

6.63

61

0.197

5

0197

0.375

9.53

0.266

6.76

69

0.2

5.08

0200

√

0.375

9.53

0.266

6.76

69

0.25

6.35

0250

0.375

9.53

0.268

6.81

70

0.3

7.62

0300

0.375

9.53

0.255

6.48

76

0.333

8.46

0333

0.375

9.53

0.245

6.22

78

0.363

9.22

0363

√

0.375

9.53

0.26

6.6

79

0.375

9.53

0375

0.375

9.53

0.265

6.73

79

0.394

10

0394

0.375

9.53

0.26

6.6

79

0.4

10.16

0400

0.375

9.53

0.293

7.44

79

0.472

12

0472

0.388

9.86

0.287

7.29

82

0.5

12.7

0500

√

0.388

9.86

0.265

6.73

81

0.667

16.94

0667

0.375

9.53

0.273

6.93

83

0.75

19.05

0750

0.388

9.86

0.273

6.93

84

0.984

25

0984

0.375

9.53

0.262

6.65

84

1

25.4

1000

0.383

9.73

0.254

6.45

84

1.2

30.48

1200

√

0.383

9.73

0.254

6.45

84

1.25

31.75

1250

0.375

9.53

0.278

7.06

84

1.5

38.1

1500

0.375

9.53

0.264

6.71

83

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 7/16" (11 mm) Diameter Lead Screw. Diameter Code 043

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.05

1.27

0050

0.437

11.1

0.362

9.19

30

0.0625

1.59

0063

√

0.436

11.07

0.358

9.09

38

0.079

2

0079

0.472

11.99

0.374

9.5

42

0.111

2.82

0111

0.437

11.1

0.327

8.31

52

0.118

3

0118

0.438

11.13

0.363

9.22

52

0.125

3.18

0125

0.438

11.13

0.357

9.07

54

0.197

5

0197

0.438

11.13

0.315

8

65

0.263

6

0236

0.433

11

0.313

7.95

70

0.25

6.35

0250

0.442

11.23

0.325

8.26

70

0.307

7.8

0307

0.445

11.3

0.343

8.71

73

0.325

8.26

0325

0.444

11.28

0.342

8.69

74

0.394

10

0394

0.446

11.33

0.331

8.41

78

0.472

12

0472

0.438

11.13

0.318

8.08

80

0.5

12.7

0500

0.452

11.48

0.327

8.31

80

0.615

15.62

0615

0.475

12.07

0.376

9.55

82

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 1/2" (13 mm) Diameter Lead Screw. Diameter Code 050

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.05

1.27

0050

0.495

12.57

0.433

11

29

0.079

2

0079

0.473

12.01

0.355

9.02

41

0.098

2.5

0098

0.5

12.7

0.383

9.73

46

0.1

2.54

0100

√

0.49

12.45

0.364

9.25

46

0.125

3.18

0125

0.5

12.7

0.374

9.5

51

0.157

4

0157

0.5

12.7

0.384

9.75

58

0.16

4.06

0160

0.5

12.7

0.388

9.86

67

0.1667

4.23

0167

0.5

12.7

0.384

9.75

58

0.197

5

0197

0.5

12.7

0.365

9.27

62

0.2

5.08

0200

√

0.492

12.5

0.366

9.3

63

0.25

6.35

0250

0.5

12.7

0.382

9.7

67

0.333

8.46

0333

√

0.497

12.62

0.362

9.19

73

0.394

10

0394

0.497

12.62

0.362

9.19

76

0.4

10.16

0400

0.497

12.62

0.364

9.25

76

0.5

12.7

0500

0.488

12.4

0.352

8.94

79

0.63

16

0630

0.5

12.7

0.374

9.5

80

0.75

19.05

0750

0.525

13.34

0.399

10.13

83

0.8

20.32

0800

0.5

12.7

0.37

9.4

83

0.984

25

0984

0.5

12.7

0.369

9.37

84

1

25.4

1000

√

0.49

12.45

0.372

9.45

84

1.5

38.1

1500

0.49

12.45

0.374

9.5

85

2

50.8

2000

0.488

12.4

0.378

9.6

87

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 5/8" (16 mm) Diameter Lead Screw. Diameter Code 062

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.1

2.54

0100

0.615

15.62

0.498

12.65

40

0.125

3.18

0125

√

0.625

15.88

0.47

11.94

45

0.2

5.08

0200

0.625

15.88

0.495

12.57

53

0.25

6.35

0250

0.625

15.88

0.469

11.91

63

0.315

8

0315

0.627

15.93

0.493

12.52

68

0.41

10.41

0410

√

0.625

15.88

0.481

12.22

72

0.5

12.7

0500

√

0.625

15.88

0.478

12.14

76

0.63

16

0630

0.625

15.88

0.491

12.47

78

1

25.4

1000

0.625

15.88

0.481

12.22

83

1.5

38.1

1500

0.625

15.88

0.499

12.67

85

1.575

40.01

1575

√

0.625

15.88

0.499

12.67

86

2

50.8

2000

√

0.625

15.88

0.499

12.67

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 3/4" (19 mm) Diameter Lead Screw. Diameter Code 075

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.0625

1.59

0063

0.75

19.05

0.671

17.04

25

0.098

2.5

0098

0.742

18.85

0.626

15.9

35

0.1

2.54

0100

√

0.746

18.95

0.624

15.85

35

0.1667

4.23

0167

0.727

18.47

0.645

16.38

47

0.197

5

0197

0.745

18.92

0.624

15.85

51

0.2

5.08

0200

0.741

18.82

0.632

16.05

52

0.25

6.35

0250

0.731

18.57

0.639

16.23

57

0.276

7

0276

0.75

19.05

0.624

15.85

59

0.333

8.46

0333

0.75

19.05

0.624

15.85

64

0.394

10

0394

0.745

18.92

0.619

15.72

67

0.5

12.7

0500

0.744

18.9

0.623

15.82

73

0.551

14

0551

0.75

19.05

0.624

15.85

73

0.591

15

0591

0.749

19.02

0.623

15.82

74

0.709

18

0709

0.78

19.81

0.65

16.51

77

0.748

19

0748

0.672

17.07

0.547

13.89

80

0.787

20

0787

0.78

19.81

0.648

16.46

78

0.8

20.32

0800

0.75

19.05

0.618

15.7

79

0.945

24

0945

0.734

18.64

0.633

16.08

80

1

25.4

1000

√

0.743

18.87

0.619

15.72

81

1.5

38.1

1500

√

0.712

18.08

0.59

14.99

84

1.969

50

1969

0.751

19.08

0.62

15.75

84

2

50.8

2000

√

0.742

18.85

0.611

15.52

84

2.4

60.96

2400

√

0.75

19.05

0.62

15.75

84

3.622

92

3622

√

0.75

19.05

0.634

16.1

87

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 7/8" (22 mm) Diameter Lead Screw. Diameter Code 087

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.2

5.08

0200

√

0.87

22.1

0.742

18.85

48

0.236

6

0236

0.848

21.54

0.773

19.63

52

0.25

6.35

0250

0.875

22.23

0.749

19.02

53

0.394

10

0394

0.875

22.23

0.741

18.82

65

0.5

12.7

0500

0.862

21.89

0.744

18.9

69

0.630

16

0630

0.875

22.23

0.741

18.82

73

0.667

16.94

0667

0.871

22.12

0.745

18.92

74

0.787

20

0787

0.875

22.23

0.741

18.82

78

0.945

24

0945

0.875

22.23

0.741

18.82

79

1

25.4

1000

0.871

22.12

0.742

18.85

80

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension. 15/16" (24 mm) Diameter Lead Screw. Diameter Code 093

Lead

Lead Code

Left Hand Avail.

Outside Diameter (For Reference)

Root Diameter (For Reference)

Efficiency %*

in

mm

in

mm

in

mm

0.05

1.27

0050

LH Only

0.938

23.83

0.874

22.2

17

2

50.8

2000

0.927

23.55

0.815

20.7

85

3

76.2

3000

0.939

23.85

0.803

20.4

86

*Listed efficiency are theoretical values based on Kerkote® TFE coated lead screws.
Shaded areas have been translated from their designed inch or mm dimension to an equivalent mm or inch dimension.

Kerkote TFE is a soft coating, a long-term dry lubricant that is optimized for softer plastics like acetals and nylons, with or without mechanical reinforcement. Lubrication to the nut / lead screw interface occurs by the nut picking up Kerkote TFE particles from the coating as well as from the migration of the internal lubricant within the plastic nut. The lubricant, although solid, also has some “spreading” ability as in fluid lubricants. Kerkote TFE coated screws provide the maximum level of self-lubrication and should not be additionally lubricated or used in environments where oils or other lubricant contamination is possible.
Black Ice™ TFE Coating

Black Ice TFE coating shares many of the benefits of Kerkote TFE but, in contrast, is a hard coating that offers exceptional durability in all types of environments, with virtually any type of polymer lead screw nut. Rather than acting as a dry lubricant, Black Ice TFE is an anti-friction coating whose surface properties displace the metal to which it is applied. Though it is not intended for use with metal or glass fiber reinforced nuts, Black Ice TFE is bonded securely to the surface of the lead screw and can withstand abrasion from contamination, rigid polymer systems, fluid impingement and wash down applications.

Available Greases

TFE coatings are intended to be used without additional lubricants. There are certain applications where external lubrication may be desired. These include the use of nut materials such as glass reinforced plastic or metal. Haydon Kerk Motion Solutions does offer a selection of greases developed specifically for these applications. Please contact a sales engineer for assistance selecting the best lubricant for your requirements.

For applications assistance or order entry, call your the Haydon Kerk Motion Solutions Leadscrew Assemblies technical advisors at 603.213.6290NOTE:
Not all thread leads are available in all screw diameters.
New nuts and leads are continually being added. Contact Haydon Kerk Motion Solutions for latest availability.

Critical Speed
This is the rotational speed at which a screw may experience vibration or other dynamic problems. See CRITICAL SPEED CHART to determine if application parameters result in speed approaching critical. To minimize critical speed problems: use a longer lead, choose a larger diameter or increase bearing mount support.

Lengths
Lengths can be specified up to 12 ft. (4M) from stock, (depending on diameter and lead). Cut to length screws are offered in 6-in increments (6-in, 12, 18,....) +1.0-in/-0-in.

Lead
Advancement per revolution. All screws are listed by lead, not pitch. Lead = Pitch x Number of Starts

Pitch
Crest-to-crest distance or one divided by threads per inch. (On a multiple start thread, the pitch equals the lead divided by the number of starts.)

Traverse Speed
The nut materials we use provide long wear-life over a wide variety of conditions. However, very high loads and/or speeds will accelerate nut wear. Special materials may be required for these situations. We offer the following guidelines for continuous duty linear traversing speeds
for optimum life:

Lead

Traverse Speed

Lead

Traverse Speed

1/10 - 1/2-in

4-in/sec.

1 - 12 mm

100 mm/sec.

1/2 - 1-in

10-in/sec.

12 - 25 mm

250 mm/sec.

1 - 2 1/2-in

30-in/sec.

25 - 60 mm

760 mm/sec.

Maximum Load
Although the Kerk® Anti-Backlash Assemblies are capable of withstanding relatively high loads without catastrophic failure, these units have been designed to operate under the loading shown in the size charts.

Efficiency
Efficiency is the relationship of work input to work output. It should not be confused with mechanical advantage. Listed efficiency are theoretical values based on Kerkote® TFE coated screws.

Torque
The required motor torque to drive a lead screw assembly is the sum of three components: the inertial torque, drag torque, and torque-to-move load. It must be noted that
this is the torque necessary to drive the lead screw assembly alone. Additional torque associated with driving frictional bearings and motor shafts, moving components, and drag due to general assembly misalignment must also be considered.

Inertial Torque:

T = I α Where I = screw inertiaj α = angular acceleration

Drag Torque:
The Kerk Anti-Backlash Assemblies are typically supplied with drag torque of 1 to 7 oz.-in. The magnitude of the drag torque is dependent on the standard factory settings or settings specified by the customer. Generally, the higher the preset force, the better the Anti-Back- lash characteristics.

Torque-to-Move:

T= LOAD x LEAD
L 2 π x EFFICIENCY

Back Driving:
Sometimes referred to as reversibility, back driving is the ability of a screw to be turned by a thrust load applied to the nut. Generally, back driving will not occur when the screw lead is less than 1/3 the diameter for uncoated screws or 1/4 the diameter for Kerkote® TFE coated screws. For higher leads where back driving is likely, the torque required for holding a load is:

T =LOAD x LEAD x BACKDRIVE EFFICIENCYb 2π

Screw Straightness:

Screw straightness is measured as Total Indicator Runout(TIR). The standard straightness for lead screws is .003-in/ft. Haydon Kerk Motion Solutions can provide tighter specifications on customer request.

All screws are hand straightened before shipping.

Typical End Machining Features
+

Customization
+

In addition to The Kerk® standard nut types, modified and complete custom configurations represent a large portion of the company’s production. Modifications may be simple changes such as different mounting hole patterns or mounting threads, small dimensional changes, or special materials. Haydon Kerk Motion Solutions can provide tremendous value by producing a multi-functional acme nut. Using custom molds and specialty machining, nuts can also include guide bushings, carriages, timing pulleys, gears, syringe components, sensor mounts and flags, encoder features, clamps and many other complimentary elements. In addition, custom designed nuts can offer quick release mounts, partial thread engagement, half nut construction or special shapes and geometries. Special materials are offered to extend the performance of our assemblies. Materials can be chosen for extreme temperature, chemical compatibility, autoclaving, agency approvals, special loadings and many other specific requirements.